a)`A(x)=-5x³+3x^4+8/11-7x²-9x`
`=3x^4-5x³-7x²-9x+8/11`
`B(x)=-4x^4-2/11+6x²+8x³+10x`
`=-4x^4+8x³+6x²+10x-2/11`
b) `A(x)=3x^4-5x³-7x²-9x+8/11`
+ `B(x)=-4x^4+8x³+6x²+10x-2/11`
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`A(x)+B(x)=-x^4+3x³-x²+x+6/11`
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`A(x)=3x^4-5x³-7x²-9x+8/11`
- `B(x)=-4x^4+8x³+6x²+10x-2/11`
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`A(x)+B(x)=7^4-3x³-13x²-19x+10/11`